Long-term biological variation in cardiac troponin I
Alan H B Wu1, Paul Akhigbe, Frank Wians
1Department of Laboratory Medicine, University of California, San Francisco, CA, USA. wualan@labmed2.ucsf.edu
Objectives:
To determine the long-term biological variation (BV) of cardiac troponin I.
Design And Methods:
Three samples separated by a mean of 8.7 ± 2.8 months from 17 patients seen in an outpatient clinic. Tropoinin I was measured using a high sensitivity assay from Singulex, Inc.
Results:
The long-term analytical, intra-assay and total variation were 15.2%, 27.9%, and 70.9%, respectively. The index of individuality (II) was 0.45, and the reference change value was +98% and -50%, respectively.
Conclusion:
The BV over 9 months was comparable to previously published results over 2 months using the same testing methodology. The II indicates that reference range values are of less value than serial testing.
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